A plasma process is essential in manufacturing a semiconductor device. In response to a demand for a high-integration and high-speed of LSI (Large Scale Integrated Circuit), a design rule is miniaturized while a semiconductor wafer becomes scaled up. Accordingly, a plasma processing apparatus is required to keep up with such miniaturization and scale-up.
However, in a parallel plate type plasma processing apparatus or inductively coupled plasma processing apparatus conventionally often used, an electron temperature is high, so that plasma damage may be inflicted on a microstructure. Further, since a high-density plasma region is limited, it is difficult to uniformly perform a plasma process on a scaled-up semiconductor wafer at a high speed.
Accordingly, a microwave plasma processing apparatus using a radial line slot antenna (RLSA) has attracted more attention since it is capable of uniformly generating plasma with a high density and a low electron temperature (see, for example, Patent Document 1).    Patent Document 1: Japanese Patent Laid-open Publication No. 2000-294550